Method of making gears



March 11 1924. 1,486,340

W. E. HOKE METHOD OF MAKING GEARS Filed March 20, 1919 Patented Mar. 11, 1924.

UNITED STATES WILLIAM E. HOKE, OF WASHINGTON, DISTRICT OF COLUMBIA.

MEIHOD OF MAKING GEARS.

Application filed March 20, 1919. Serial in. 283,869.

To all whom it may concern:

Be it known that I, WILLIAM E. Hons, a citizen of the United States, residing at Washington, District of Columbia, have inl vented certain new anduseful Improvements in Methods of Making Gears, of which the following is a specification.

My invention relates to a method of making gears and has for its object the provision of a method by which may be made accurately shaped gears internal or external, of hardened or unhardened metal, all the gears being of identical configuration within any desired degree of accuracy. a The method employed is based on the prin ci les described in my application 252,073 fi ed Aug. 30, 1918.

The method will be understood from the accompanying description and drawings in 90 which Fig. 1 is a sectional elevation s owing a lapping spur gear in mesh with the internal gear which is being lapped.

Fig. 2 is a sectional elevation on a plane at right angles to the plane of Fig. 1 and on a smaller scale.-

As is well understood an external gear will mesh roperly with an internal gear pro vided it has a number of teeth less by two or more than the number of teeth on the internal gear.

Accordingly if it is desired to accurately shape the teeth of an internal ear, particularly such as are made of her ened steel or iron, I assemble a number of such hardened internal ar blanks A in contact side by side and re erably contained in a holder, B, in the orm of a sleeve or other device that insures their bein held in concentric relation. I also provide a ongfxternal gear C of castiron or other suite 10 metal, having accurately formed tooth surfaces of the same pitch as-those to be formed on the internal gear teeth.

Except for mathematicall accurate work, the lapping gear need not h s of'hi h accuracy, as the system of symmetrical istribution of errors, as herein described, produces gear teeth of equal acin and correct curves, more than sufiiclent or commercial pur oses.

is lap ing ar is, by any of the usual methods, c arge with a suitable abrasive, and is of less diameter and has a smaller number of teeth than the internal gear. The I lapping gear is then inserted into and its teeth brought into mesh with the teeth of the internal gears and held in contact therewith by any suitable pressure means. The containing sleeve or other device having been locked by any appropriate means, the lapping is effected, a suitable lubricant being use by reciprocating the stack of interns gears endwise and at the same time slowly revolving them about the lapping gear, which is also mounted to rotate. The intermeshed gears are kept in lapping engagement by the application of suitable pressure, either by gravity or by spring pressure. After a suitable period of rinding in this first relation, the container is unlocked and the internal gears may then be turned into a relatively diflt'erent position to each other, so that other teeth are matched. The operation is then repeated'as often as may be necessary. From time to time the relative positions of the internal gears in the stack or row are also changed and they are also reversed side for'side.

By this repeated turning, interchanging of position and side-for-side reversal in combination with the lapping action due to the longitudinal reciprocation and relative rotation of the intermeshed gears, the teeth of the internal gears are provided with surfaces which are of accurate curvature, which are accurately spaced, concentric with the axis of the gear and perpendicular to the faces of the disks and adapted to mesh properly with any external gear having a ess number of teeth of the same pitch. And each gear is exactly identical with every other gear of the series.

It is obvious that this method might be reversed b using an internal gear having precisely s aped tooth surfaces as the lapping means for producing accurate teeth on a hardened steel'external gear, and either method is included within the scope of my claims.

It is also apparent that the stack or row of blanks might be held stationary and the lap ingmgear be reci rocated, or that both mig t reciprocate during the rotation.

Nor is my invention limited to the production of precision gear teeth,as other forms of s mmetrical corrugations either external or internal may be produced by application of the same principle of operation.

As the are, whether internal or external, have be sued teeth of precise shape, they I as punches or dies for forming gears .either.

are available not only for use as gears, but

external or internal, out of softer metal.

The same principle of 0 eration'may also be' applied to spiral or he ical gears, either external or internal.

The terms lap and lap ing are intended to include not only a rading with surfaces charged with abrasive, but also,

other abrading action.

I claim:

1. The method of making gears which consists in lapping a series of gear blanks by means of an intermeshed gear shaped lap, the lappi operation comprisin repeated change in t e position of the blan s relative to each other and to the lapping ar, and also relative longitudinal and rotative movements of the blanks and lapping gear.

2. The method of making gears which consists in lapping a series of gear blanks by means of an intermeshed gear shaped lap,

the lapping operation com rising repeated inter-c a 'ng of the bla relative longitudinal and rotative movements of the blanks andlapping. gear.

3. The method of making gears which consists in lapping a series of gear blanks by s of the series, reversal o the blanks side for side, and also which the blanks are internal gears and the la p' gear is an external gear.

l he method of making an internal gear of hard metal. which consists in lapping the tooth surfaces thereof into accnrate configuration by means of an external gear la' having accurately. formed teeth and charge with abrasive, held in yielding engagement with the internal gear, and unpartmg to said gear and lap relative rotative and longitudinal movement.

8. The method of finishing ears which consists in intermeshing a num r of ears to be finished with a gear of accurate orm, one gear or set of gears having internal teeth and the other set of gears or gear having external teeth, and imparting to said .intermeshed gears while in yielding enga ement and under abradin conditions, re ative rotative and longitudinal movement.

In testimony whereof I afiix my signature. 1

WILLIAM E. HOKE. 

